1. Field of the Invention
The present invention relates to an apparatus for use in assembling a frame having slotted side members connected by corner brackets. The invention is particularly useful in assembling a flange frame for an air conditioning or heating duct.
2. Background of the Invention
A typical flange frame of a duct for use in air conditioning and heating systems comprises four flat corner brackets that join together four side members. The corner brackets typically have ends that are inserted into slots formed in the ends of the side members.
Duct flange assemblies are difficult to assemble. Various attempts have been made in the prior art to reduce the time and effort required to assemble a duct flange. Most attempts to improve the ease with which duct flanges are assembled have involved improved designs for the corner brackets of the ducts.
For example, U.S. Pat. No. 5,069,484 discloses a corner bracket having pair of locking means formed thereon. When ends of the corner brackets are slid into slots formed into a pair of side members, the locking means engage complementarily formed locking means formed in the edge members. U.S. Pat. No. 5,005,879 discloses corner brackets having folding tabs formed thereon. Ends of the corner bracket are inserted into slots of a pair of side members, and the tabs are folded outward to stabilize the end members in relation to the corner bracket. U.S. Pat. No. 5,165,730, meanwhile, discloses a pair of abutting corner brackets for each corner of a duct flange. When complementary locking means of the abutting brackets engage, the legs of the abutting brackets separate to increase the securing force of the brackets against the side members of the duct.
Despite attempts to improve the design of the corner brackets of a duct flange, problems persist with existing duct flanges. The improved corner brackets proposed in the prior art require specialized locking means, latches, tabs, and the like. Not only are brackets having these miniature and sophisticated components susceptible to breakdown, they are also difficult and costly to manufacture, requiring precise machining.
An apparatus for assembling parts of a duct flange is disclosed in U.S. Pat. No. 5,283,944. The apparatus operates by forcing corner brackets of a duct flange flush against coplaner surfaces of a pair of adjoining side members where they are received by clasps. Like other corner brackets recently proposed, the corner brackets used with the apparatus of U.S. Pat. No. 5,283,944 have sophisticated components and require precision manufacturing.
There remains a need for an apparatus for use in assembling a frame having slotted side members connected by corner brackets, which facilitates quick and effective assembly of parts of the frame, and which does not require for operation specialized or precision manufacturing of the component parts.